Adjustable propeller



y 1931- J. w. M CLATCHlE ADJUSTABLE PROPELLER Filed March 7, 1928 JNVENTOR.

A TTORNE Y.

Patented May 5, 1931 T f rl.

,easss .A'DJ'USTABLE PROPELLER Application filed March 7; 1928. Serial No. ,708.

This invention relates to propellers particularly adapted for aeroplane propulsion, and has for its object the provision of means whereby the pitch of the propeller blades 5. may be readily adjusted while the aeroplane is in flight, in order to accommodate the propeller to varying meteorological conditions.

It is a further object of the invention to provide propeller blade adjusting means 0 which is subject to extremely accurate control, and which provides an operating connection of simple but practical construction adapted to uniformly adjust the plurality of blades which form a propeller.

More particularly it is an object of the invention to provide propeller blade adjusting means including a fluid pressure control,

whereby increase in the fluid pressure is adapted to rotate the propeller blades on their longitudinal axes and in a direction against the wind pressure caused by operation of the. propeller, and relief of saidfluid pressure permits reverse axial rotation of the blades by the wind pressure, so that a positive control for the fluid pressure insures accurate adjustment of the blades.

Further objects of the invention will be readily understood from the following description of the accompanying drawings, in which:

. Fig. 1 is a front elevation of my adjustable -propeller, partly in transverse section and showing the control mechanism in somewhat a diagrammatic form; i

Fig. 2 is a side elevation of the propeller, partly in axial section.

Fig. 3 is a detail section on the line of Fig 2. p o ig. 4 is a fragmentary axial section through a propeller showing a'modified construction. t,

I have illustrated the invention as embodied in a propeller adapted for, aeroplane propulsion, the main shaft 1 of the aeroplane engine projecting from fuselage 2 and having a hub 3 keyed thereon with the pair of usual propeller blades 4 projecting from opposite sides of the hub. The instrument board of the aeroplane is preferably provided with a panel -5 carrying the control and indicat-' ing mechanism for rotatably adjusting the propeller blades on their longitudinal axes.

The inner ends of blades 4 are preferably adapted for threaded reception in bores 8 of hub 3, the threaded engagement being shown at 9; and connecting means which are provided between the inner ends of the pair of blades are so arranged that rotary adjustment of one of the blades on its longitudinal axis will cause a similar rotary adjustment of the other blade in the opposite circumferential direction in order-to adjust the working pitch of the propeller. f

As an instance of this arrangement, a pair of rock arms 11 may be medially pivoted at 12 in suitable recesses 13 in hub 3, so that the ends of each rock arm overlies the ends of the pair of propeller. blades as shown in Fig. 2, with the pair of rock arms overlying the blades at diametrically opposite oints as shown in Fig. 3. The ends of the lades are connected to the overlying ends of the rock arms by pins 14 projecting radially .from the blade ends and received in bearin 's 15 in the ends of the rock arms, so that roching of arms 11 in opposite. directions by rotary adjustment of one of the bladeswill A cause a corresponding opposite rotation of the opposite blade.

It will be noted that rotary adjustment of the propeller blades will also cause slight axial shifting of the blades as a result of their threaded engagement 9, and by making the -.th-reads of theproper pitch, the parts may be so arranged that the slight axial shifting of the propeller blades will compensate for the shortening of the axial distance between pivots 12 and 14 when arms 11 are rocked,- thereby insuring adjustment of the blades without binding action at the bearings 15.

The means for rotatably adjusting the propeller blades on their longitudinal axes 1s preferably-a fluid pressure -means, and for this purpose the hub 3 is providedwith an. axial cylinder 20 in longitudinal alinement with one of the pins 14, and a piston 21 reciprocates in the cylinder and is connected by rod 22 to the pin. An axial enlargement 60 on the face of hub 3 may counterbalance the cylinder 20. The parts are preferably so so as to vary the pitch of the propeller in the direction opposite to that of the air pressure caused by the propeller, and relief of the fluid pressure will permit piston 21 to freely move in the opposite direction in accordance with reverse opposite rotation of blades 4 which will result from the wind pressure against the blades, thereby varying the pitch of the propeller in the opposite direction. It will thus be seen that by controlling the fluid pressure and its relief the propeller may be adjusted to any desired pitch, and in practice the limits of the adjustment are preferably determined by stops 30 adapted for abutment by one of the pins .14.

The fluid pressure control is preferably regulated from the panel 5 on the instrument board, and for this purpose a storage receptacle 40 for a suitable fluid such as oil communicates with a pump 41 which is mounted on the back of panel 5, and the pump supplies the oil under pressure to a suitable pressure controlled indicator 42 through a line 43 and thence to cylinder 20 so as to shift the piston 21. The pressure may be relieved by means of a valve 44 in order to permit reverse movement of the piston, and this valve is preferably provided in a by-pass 45 extending from indicator 42 to the tank 40, and the line 39 leading from the tank to pump 41 is provided with a check valve 46.

The pump 41 is preferably actuated by a hand-lever 47 projecting from panel 5; and with valve 44 closed, operating the pump is adapt-ed to draw fluid past check valve 46 and force the same through the indicator 42 and thence to cylinder 20, with the pressure which is built up transmitted to the indicator which is preferably calibrated to denote Low, Medium, and Extreme propeller pitch, and the pump lever being actuated until the pitch of the propeller is reduced to any desired pitch as shown on the indicator. When it is subsequently desired to increase the pitch of the propeller, the valve 44 is opened so as to relieve the pressure through by-pass 45, and the valve is preferably controlled by a hand-lever 50 which cooperates with a dial 51 mounted on panel 5 and indicating the open and closed positions of the valve. The valve is held in open position before again closing the same, for an interval adapted to produce the desired reduction in pressure for increasing the propeller pitch to either Medium or Extreme, and such reduction in the pressure is transmitted to indicator '42 through by-pass 45 so that the indicator will denote the increase in the propeller pitch as regulated by the opening of the valve. With the-valve re-closed the pressure may be again increased by operating the hand-lever 47 so calibration which reads Extreme.

' 3 may communicate with the cylinder 20, with said bore opening at its opposite end into an annular bore 56 111 the face of hub 3 which is adjacent fuselage 2. The bore 56 is concentric with drive shaft 1 and is adapted to receive a usual U-sha ed packing annulus 57 which projects from uselage 2, and the pipe line 48 opens into the U-shaped packing so that the pressure in the line expands the packing to provide a fluid tight rotary fit for hub 3, and the pressure in the line is thus trans-- mitted through bore 56 to the cylinder 20 for adjusting the propeller pitch.

It will he understood that when the fluid pressure is entirely relieved by opening valve 44, the blades 4 are turned by the wind pressure to the limit of their adjustment which causes an increase in the propeller pitch, and that when the pressure is thus entirely relieved the indicator is in position opposite its When valve 44 is closed and pump 41 is actuated, the pressure which is built up will turn indicator 42 in the direction toward its calibration marked Medium and from thence toward its calibration marked Low, with said movement of the indicator denoting the corresponding decrease in the pitch of the propeller until the blades are finally at their opposite limit of adjustment at which time indicator 42 will be opposite the marking denoted Low. By then turning hand-lever 50 so as to open and then re-close valve 44 with the valve remaining open for a desired interval, the pressure is reduced so that indicator 42 will move in the opposite direction toward its calibration Medium and thence toward its calibration Extreme, with the pltch of the propeller correspondingly increased by the wind pressure generated by the propeller revolution.

In the modification of the invention shown in Fig. 4 the propeller blades are preferably adapted forsuch adjustment as will com pletely reverse the propeller. As an instance of this arrangement the piston rod 22 may form a rack adapted to mesh with a pinion 14 on the inner end of one of the blades 4, and said pinion is connected by reversing gearing 11 which is shown as including an idler 11*, with a pinion 14 on the inner end of the opposite blade 4. By this arrangement reciprocation of piston 21 as previously described is adapted to reversely rotate blades 4 so as to adjust the propeller pitch and finally reverse the propeller if so desired, it being understood that the indicatin mechanism which is used in connection wit such a reversing mechanism, will be suitably calibrated to indicate both partial adjustments and complete reversal of the propeller, with the indicating and Control mechanism arranged as previously described and so constructed that complete relief of the fluid pressure will permit the Wind pressure to so increase the propeller pitch as to finally reverse the propeller. v

I claim:

1. The-combination of a propeller including a hub and diametrically opposite propeller blades rotatable on their longitudinal axes, a rock arm medially pivoted in the hub and connected at its respective ends to the respective propeller blades so that swinging movement of said roc'k arm will reversely rotatably adjust the propeller blades to vary the pitch of the propeller, a cylinder in the propeller hub, a piston in said cylinder operatively connected to said rock arm, and a fluid pressure conduit extending through the .hub and communicating with the cylinder for actuating the piston.

2. The combination of a propeller including a hub and propeller blades threaded into the hub, and an arm medially pivoted With relation to the hub and adapted to be rocked on the axis formed by said pivot, the ends of the arm being connected to the respective blades for reversely rotating the blades to adjust the pitch of the propeller by rocking movement of the arm, and the threaded engagement for the propeller blades being adapted to axially shift the blades by the reverse rotation thereof so as to compensate for the rocking movement of the arm.

3. Thecombination of a propeller including a hub and propeller blades threaded into the hub, and an arm medially pivoted on an axis transverse to that of the hub and adapted to be rocked on said axis, the ends of the arm being connected to the respective blades for reversely rotating the blades to adjust the pitch of the propeller by rocking movement of the arm, and the threaded engagement for the propeller blades being adapted to axially shift the blades by the reverse rotation thereof so as to compensate for the rocking movement of the arm.

4. The combination of apropeller includ- 7 ing. a hub andpropeller blades threaded into the hub, and an arm medially pivoted-on an axis transverse to that of the hub and adapting a hub and propeller blades rotatable on their longitudinal axes, and an'arm medially pivoted on an axis transverse to that of the huband adapted to be rocked on said axis, the ends of the arm being connected to the respective blades for reversely rotating the blades to adjust the pitch of the propeller by rocking movement of the arm.

6. The combination of a propeller including a hub and propeller blades rotatable on their longitudinal axes, and an arm medially pivoted on an axis transverse to that of the hub and adaptedto be rocked on said axis, the arm overlying one side of the blades with the ends of the arm connected to the respective blades for reversely rotating the blades to adjust the pitch of the propeller by rocking movement of the arm.

In testimony whereof he has aflixed his signature to this specification.

JOHN W. MACCLATCHIE. 

